1. Field of the Invention
The present invention relates to a multi-eye image display apparatus with optical systems each for guiding an image (image information) being displayed on a compact display device for example such as a liquid crystal display device, a CRT, etc. to form an enlarged virtual image thereof in front of an observer so that the observer can observe the virtual image.
2. Related Backaround Art
Large CRT display apparatus, projection TVs, etc. have been conventionally used as apparatus for displaying a large-screen image with presence from image information displayed on an image display device such as a liquid crystal. These apparatus, however, had problems of various restrictions on operating circumstances; for example, they needed a large space, it was hard to observe a good image without dark surroundings, etc.
Because of the problems, various multi-eye image display apparatus have been recently proposed in such an arrangement that beams are projected from images displayed on image display devices directly to the eyes (the observer's pupils) through optical systems disposed very close to the face so as to permit the observer to observe large-screen image information, a stereoscopic image, or a panorama image.
Among the multi-eye image display apparatus, a goggle-type head mounted display (hereinafter referred to as "HMD") to be mounted on the head is relatively easy of observation of virtual large-screen images as enlarged from images displayed on compact liquid crystal displays (hereinafter referred to as "LCD") by optical systems such as lenses.
For example, Japanese Patent Application No. 5-92113 discloses a multi-eye image display apparatus for HMD using changing means which can change a convergence angle of displayed images for the left and right eyes whereby the apparatus can display not only a stereoscopic image but also a two-dimensional panorama image in a variable aspect ratio and can also display a mixed image of a stereoscopic image and a two-dimensional image, and further using combiner elements for superimposing image information of external view on such image information whereby the observer can observe the both images' information at a time.
In the conventional multi-eye image display apparatus, for example, supposing an angle of view of the optical systems is 30.degree. and the position of the virtual images of the displayed images is located 1 m ahead of the observer, the LCDs a little less than an inch are perceived as displays of about 30 inches 1 m ahead on calculation. However, though the angle of view was actually 30.degree., there was no information giving the sense of distance, "1 m ahead." Because of this, the observer was not always able to perceive them as displays of 30 inches 1 m ahead, but tended to perceive that there were compact displays in front of the eyes, raising a problem of being hard to realize appreciation with presence on a large screen, with feeling of being more natural, but without feeling of fatigue.
In addition, the conventional multi-eye image display apparatus were so arranged that, for example, the convergence angle of left and right displayed images was changed to shift the virtual images in the horizontal direction whereby an overlapping region of the left and right images was changed so as to change the aspect ratio of a displayed image for the both eyes. In this case, for fusion of the left and right images depending upon the overlapping region, common parts of the displayed images were finally left to human processing by brains after by the retinas. This caused a problem that it was difficult for the observer to naturally follow a change in the aspect ratio upon switching of scenes, resulting in the observer's feeling tired and thus making long-period observation difficult.